Conventionally, there has been widely known a control apparatus for an internal combustion engine equipped with a supercharger in which two turbo chargers are serially disposed in exhaust and intake passages (series-type 2-stage supercharger) (see, for example, Japanese Patent Application Laid-Open (kokai) No. 2007-263033). Specifically, the apparatus disclosed in this document includes a first turbo charger, and a second turbo charger which is greater in size than the first turbo charger. The first turbo charger includes a first turbine disposed in the exhaust passage and driven by the energy of exhaust gas; and a first compressor disposed in the intake passage and driven by the first turbine. The second turbo charger includes a second turbine which is disposed in the exhaust passage at a position downstream of the first turbine, is driven by the energy of exhaust gas, and is greater in size (capacity and outer diameter) than the first turbine; and a second compressor which is disposed in the intake passage at a position upstream of the first compressor, is driven by the second turbine, and is greater in size (capacity and outer diameter) than the first compressor.
The apparatus disclosed in the above-mentioned document includes a first exhaust bypass passage which establishes a bypass between a portion of the exhaust passage located upstream of the first turbine and a portion of the exhaust passage located between the first and second turbines; and a first intake bypass passage which establishes a bypass between a portion of the intake passage located between the first and second compressors and a portion of the intake passage located downstream of the first compressor. A first exhaust control valve for adjusting the minimum opening sectional area of the first exhaust bypass passage (first exhaust bypass area) is disposed in the first exhaust bypass passage. A first intake control valve for adjusting the minimum opening sectional area of the first intake bypass passage (first intake bypass area) is disposed in the first intake bypass passage.